Terminal clamp for messengrer cable



- Aug. 11, 1964 J. w. SCHR-EYER 3,144,500

TERMINAL CLAMP FOR MESSENGER CABLE Filed Jan. 23, 1962 50 fflZ/l? for.

$572 Mjc/Izreyer United States Patent Office 3,144,503 Patented Aug. 1l, 1964 3,144,501) TERMINAL CLAMP FOR MESSENGER CABLE John W. Schreyer,Sleepy Hollow Manor, 111., assignor to Reliable Electric Company,Franklin Park, 111., a corporation of Illinois Filed Jan. 23, 1962, Ser.No. 168,093 9 Claims. (Cl. 174-41) This invention relates to'an improvedclamp for messenger cable or the like.

The term messenger cable" refers to a Combination of two elements, ofwhich the cable element is a sheathed conductor and of which themessenger element serves as a support for the former. This two elementarrangement is used in power distribution and in communication work.

My invention is described herein with respect to its applicability toshielded communication cable because my invention is particularlyadapted for use in connection with a ready access type of terminaldesigned for integrated messenger cable and used in communication work.

However, my invention is also applicable for use with unshieldedcommunication cable and for use with power cable, which is generallyunshielded.

In a shielded communication cable, the cable element comprises a bundleof conductor pairs, or core, and a sheath. The sheath includes ametallic grounded shield and an insulating jacket. In integratedmessenger cable, the messenger and the cable are continuously connectedby a common extruded jacket.

When the sheath is stripped from the cable, in making connections or asplice, the two ends of the grounded shield must be electricallyconnected. According to my invention, this electrical connection is madethrough the messenger, and the clamp electrically connects the groundedshield with the messenger.

A ready access terminal is a housing which is suspended from theintegrated messenger cable and which contains terminal blocks so thatconnections can be made between the various conductor pairs of the cableand one or more service wires. The casing part of the ready accessterminal protects the'connections from the weather.

The clamp which forms the subject matter of my invention is mounted, oneat each end, on a base portion of the ready access terminal and engagesthe messenger so that the terminal as awhole can be supported by themessenger. One advantage of this arrangement is that both clamps and themessenger are contained within the terminal housing.

An object of my invention is to provide an improved messenger engagingclamp which also cooperates with the cable portion of the messengercable in a novel way so as to hold the same firmly with respect to theterminal structure as a whole.

A further object is to provide a single clamp for both the messenger andthe cable which provides a ground connection for the cable sheath.

Another object is to provide an improved clamp of the type describedwhich is capable of gripping several different sizes of messenger cableand in which this adjustable feature does not detract from theeffectiveness of the cable supporting or sheath gripping arrangement.

Other objects, features and advantages will become apparent as thedescription proceeds.

With reference now to the drawings in which like reference numeralsdesignate like parts:

FIG. 1 is a front elevation of a clamp embodying my invention andshowing also the cooperation of the clamp with the cable and messenger;

FIG. 2 is a side view of the clamp alone;

. FIG. 3 is an elevational view of an integrated messenger cable showingthe manner in which it is prepared for cooperation with the clamp;

FIG. 4 is an elevation of a ready access terminal, illustrating anintended use of my clamp; and

FIG. 5 is a section taken along line 5 of FIG. 1.

The messenger cable 10 shown in FIG. 3 is an integrated messenger cable.It comprises a cable 11 and a messenger 12. The cable 11 comprises acore 13 and a sheath. The sheath is in two layers; the inner layer is ofmetal and provides a grounded shield 14, and the outer layer is aninsulated jacket 15.

The messenger 12, which is preferably made of a plurality of steelstrands, is provided with a jacket 16. The cable 11 is connected to themessenger 12 by a web 17 of jacketing material. The jackets and web 15,16 and 17 are integrally formed by an extrusion process.

In preparing the cable for cooperation with the clamp, a portion of thecable sheath 15 isremoved and one or more slits 28 are formed in thesheath so as to provide an expanded marginal sheath portion, referred toherein as the tab 19. The tab 19 comprises the inner shield 14 and theouter jacket 15, and it may be in one or more sections, depending on thenumber of slits. Also, a portion of the messenger jacket 16 is removedat a point right above the tab 19.

The clamp 20 shown in FIGS. 1 and 2 comprises clamping members 21 and22. Each clamping member is provided with an arcuate shaped jaw portion23, with a top lug portion 24, and with a lower lug portion 25. The twoclamping members are connected to each other by a top screw 26 and alower screw 27 so that the two clamping members may be brought togetherin clamping relationship. The lower end of the clamping member 21 isextended downwardly to provide a mounting bracket 28.

The material of each clamping member which is disposed between the toplug portion 24 and the jaw portion 23 is shaped to provide a clampingportion 29. The clamping portions 29 react against each other, but thejaw portions 23 react against a third element.

Disposed between the two jaws 23 is a reaction ring 30. This is not aclosed ring, but is formed of strip material, preferably corrugated asat 32 (FIG. 5) and the ends are brought upwardly and curved toward eachother. to form jaw portions 31. In other words, the reaction ring as awhole is of a figure 8 shape which corresponds generally to the figure 8shape of the integrated messenger cable 10.

The tab 19 of the cable 11 is clamped between the jaw portions 23 andthe reaction ring 30. The messenger 12 is disposed between the jawportions 31 of the reaction ring, and the jaw portions 31 are urged intoengagement with the stripped surface of the messenger 12 by means of theclamping portions 29 of the clamping members 21 and 22. This arrangementprovides electrical contact between the messenger 12'and the groundedshield 14, since both are engaged by the reaction ring 30 which, beingof metal, is a conductor.

As shown-in FIG. 5, the jaw portions 23 of the clamping members may alsobe serrated so that the tab is gripped between two serrated members, thereaction ring 30 and the jaw portions 23.

It will be observed in FIG. 1 that the core 23 is not gripped by anyelement. The reaction ring 30 is of a larger diameter than the core 13,but the core 13 is supported by means of the tab 19.

In operation, after the cable has been prepared as shown in FIG. 3, thereaction ring is'placed around the core 13 at a point beneathth'e tab19. The jaw portions 31 of the reaction ring are placed around themessenger 12 at the point where the jacket has been stripped therefrom.Then the two clamping members 21 and .22, in

are tightened up, but in the final stages of tightening,

the screw 26. is screwed up tighter than the screw 27 so that themessenger will be firmly clamped between the jaw portions 31. Then thelower screw 27'is tightened up so that the tab is clamped between thejaw portions 23 and the reaction ring 30. It will be seen from theforegoing that a considerable variation in messenger size will have someeliect on the diameter of the reaction ring 30, but the diameter of thereaction ring has nothing to do with the clamping action exerted on thetab 19.

One intended use of the clamps is in connection with a ready accessterminal 36 shown in FIG. 4. Here the clamps 20 are shown in dottedlines, one being located at each end of the terminal. The ready accessterminal includes a base portion upon which the bracket '28 can bemounted by means of a suitable screw or rivet. In FIG. 1,'the baseportion 37 is indicated in dotted lines together with a screw 38.

The ready access terminal 36 is provided at each' end with sleeveportions 39 through which the integrated messenger cable 10 extends. beprovided to clamp the sleeve portions 38 against the integratedmessenger cable 10. i v

In some types of ready access terminal, a second and smaller cable maybe brought in. For example, the ready access terminal may be locatedclose to a pole, and a branch cable which is supported bythe pole isbrought into the ready access terminal. The branch cable is not amessenger cable; furthermore, since the span of the branch cable may beonly two or three feet, it is not necessary to grip the branch cabletightly. Therefore, a means is desired to hold the end of the branchcable in the ready access terminal. Such a holding means is provided byextending the clamping member 22 downwardly below the lower lug portionto provide an auxiliary clamping portion 41 which cooperates with theoppositely disposed shank, of the mounting bracket on the clampingmember 21.

Although there is no adjustability with respect to the auxiliaryclamping portion, it is an added convenience when the size of the branchcable is such that it can. be held firmly by the auxiliary clampingportion 41. In this connection, tape can be used to bring an undersizedcable up to the proper diameter.

Although illustrated in connection with a particular type of terminaL'myclamp is suitable for use in other types of installations which requiremeans for supporting a stripped cable from the messenger. This needarises in various kinds of terminal and splicing operations.

Although only a preferred embodiment of my invention has been shownherein it will be understood that various modifications and changesmaybe made in the construction shown without departing from the spirit ofmy invention as'pointed out in the appended claims.

Iclaim:

1. A clamp for stripped and tabbed messenger cable, whereof the sheathof the cable portion is provided with an inner grounded shield 7 saidclamp comprising first and second clamping members each having upper andlower lug portions, a jaw portion disposed between said upper and lowerlug portions, and a clamping portion disposed between said jaw portionand said upper lug portion, screw threaded means extending through saidupper and lower lug portions to draw said clamping members together, I

Suitable clamps 40 may a reaction ring disposed between the oppositelyfacing jaw portions of each clamping member and cooperating with saidjaw portions to provide a clamping couple for the sheath tab of saidcable portion,

said reaction ring being adapted to engage the grounded shield of saidsheath tab in electrical conducting relationship,

the ends of said reaction ring extending upwardly into the space betweensaid clamping portions and being shaped to provide messenger engagingjaw portions,

and said reaction ring jaw portions being adapted to engage saidmessenger in electrical conducting relationship.

2. A clamp for stripped and tabbed messenger cable comprising first andsecond clamping members each having upper and lower lug portions, afirst jaw portion disposed between said upper and lower lug portions,and a clamping portion disposed between said jaw portion and said upperlug portion, screw threaded means extending through said upper and lowerlug portions to draw said clamping members together,

a reaction ring disposed between the oppositely facing jaw portions ofeach clamping member,

said reaction ring having second jaw portions extending into the spacebetween said twoclamping portions of said clamping member, I

said reaction ring cooperating with said first jaw portions to provide aclamping couple for the sheath tab of the cable portion of saidmessenger cable,

and said second jaw portions being adapted, when compressed by theclamping portions of said clamping members, to engage the messenger ofsaid messenger cable,

the core of said cable portion being loosely disposed within saidreaction ring.

3. A clamp for stripped and tabbed messenger cable said clamp comprisingfirst and second clamping members each having a first jaw portion, I anda clamping portion disposed above said jaw portion,

a reaction ring disposed between the oppositely facing jaw portions ofeach clamping member,

said reaction ring having second jaw portions extending into the spacebetween said two clamping portions of said clamping member,

a first screw connecting said clamping members at a point above saidclampingportions for urging said clamping portions and said second jawportions into engagement with the messenger of said messenger cable, andV a second screw connecting said clamping members at a point below saidfirst jaw portions for urging said first jaw portions into engagementwith said reaction ring in order to clamp the sheath tab'of saidmessenger cable when said sheath tab is disposed between said reactionring and said first jaw portions,

the core of said cable portion being loosely disposed within saidreaction ring.

4. A clamp as claimed in claim 3 in which one of said clamping membersis extended downwardly below said second screw to provide a mountingbracket for said clamp.

5. A clamp as claimed in claim 4 in which the other one of said clampingmembers is extended downwardly to provide, in combination with saidmounting bracket, an auxiliary clamping portion.

6. A clamp as claimed in claim 3 in which said first jaw portion andsaid reaction ring have serrated surfaces.

7. A clamp as claimed in claim 1 in which said split reaction ring isformed of corrugated sheet metal, the corrugations thereof running fromone of said ends to the other.

8. In combination with a cable having an exposed core and anelectrically conducting sheath tab,

a messenger for supporting said cable,

first clamping means engaging said messenger,

an electrically conducting reaction ring surrounding said core beneathsaid sheath tab,

second clamping means for urging said sheath tab into electrical contactwith said reaction ring,

said reaction ring including a portion which extends between said firstclamping means and said messenger to provide an electrical connectionbetween said sheath tab and said messenger, and

means connecting said first and second clamping means so that said cablecan be suspended from said messenger.

9. A clamp for stripped and tabbed messenger cable, whereof the sheathof the cable portion is provided with an inner grounded shield saidclamp comprising first and second clamping members, each clamping memberbeing shaped to provide upper and lower lug portions,

a jaw portion disposed between said upper and lower lug portions,

and a clamping portion disposed between said jaw portion and said upperlug portion,

screw threaded means extending through said upper and lower lug portionsto draw said clamping members together,

a reaction ring disposed between the oppositely facing jaw portions ofeach clamping member and cooperating with said jaw portions to provide aclamping couple for the sheath tab of said cable portion,

said reaction ring being adapted to engage the grounded shield of saidsheath tab in electrical conducting relationship, and

means providing an electrical connection between said reaction ring andsaid messenger.

References Cited in the file of this patent UNITED STATES PATENTS1,608,184 Rumble Nov. 23, 1926 1,631,719 Chandler June 7, 1927 2,199,892Metcalf May 7, 1940 2,595,857 Kinsel May 6, 1952 2,891,101 Koliss June16, 1959 2,961,479 Bertling Nov. 22, 1960

8. IN COMBINATION WITH A CABLE HAVING AN EXPOSED CORE AND ANELECTRICALLY CONDUCTING SHEATH TAB, A MESSENGER FOR SUPPORTING SAIDCABLE, FIRST CLAMPING MEANS ENGAGING SAID MESSENGER, AN ELECTRICALLYCONDUCTING REACTION RING SURROUNDING SAID CORE BENEATH SAID SHEATH TAB,SECOND CLAMPING MEANS FOR URGING SAID SHEATH TAB INTO ELECTRICAL CONTACTWITH SAID REACTION RING,